In recent years, after an embedded device such as a DVD device and a TV device is released, when a deficiency is found in software (including firmware), a method of rewriting firmware in the past to firmware in which the deficiency is solved to solve the problem is generally adopted. The firmware indicates all data stored in advance in a nonvolatile storage area of the embedded device. Such firmware update is disclosed in, for example, Patent Literature 1, Non Patent Literature 1, Non Patent Literature 2, and the like.
Patent Literature 1 discloses a firmware updating system for replacing entire firmware. When the firmware is updated through a network in order to replace the entire firmware, since it is necessary to deliver all firmware images of a new version, a data size which should be delivered is large.
Non Patent Literature 1 discloses a technique for extracting a difference between data of an old version and data of a new version. When firmware is updated through a network, if only an update difference of the firmware is delivered using this technique, a delivered data size can be reduced.
Non Patent Literature 2 discloses a software updating program often used in Linux. With the program, software is managed in packet unit and an updated software package is distributed.